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  • Figure 55-1 The digital multimeter should be set to read DC volts, with the red lead connected to the positive (+) battery terminal and the black meter lead connected to the negative (-) battery terminal.
  • Figure 55-2 A scan tool can be used to diagnose charging system problems.
  • Figure 55-4 This accessory drive belt is worn and requires replacement. Newer belts are made from ethylene propylene diene monomer (EPDM). This rubber does not crack like older belts and may not show wear even though the ribs do wear and can cause slippage.
  • Figure 55-5 Check service information for the exact marks where the tensioner should be located for proper belt tension.
  • Chart 55-1 Typical belt tension for various widths of belts. Tension is the force needed to depress the belt as displayed on a belt tension gauge.
  • Figure 55-7 Testing AC ripple at the output terminal of the alternator is more accurate than testing at the battery due to the resistance of the wiring between the alternator and the battery. The reading shown on the meter, set to AC volts, is only 78 mV (0.078 V), far below what the reading would be if a diode were defective.
  • Figure 55- 9 A mini clamp-on meter can be used to measure alternator output as shown here (105.2 Amp). Then the meter can be used to check AC current ripple by selecting AC Amps on the rotary dial. AC ripple current should be less than 10% of the DC current output.
  • Figure 55-10 Voltmeter hookup to test the voltage drop of the charging circuit.
  • Figure 55-11 A typical tester used to test batteries as well as the cranking and charging system. Always follow the operating instructions.
  • Figure 55-12 The best place to install a charging system tester amp probe is around the alternator output terminal wire, as shown.
  • Figure 55-13 Replacing an alternator is not always as easy as it is from a Buick with a 3800 V-6, where the alternator is easy to access. Many alternators are difficult to access, and require the removal of other components.
  • Figure 55-14 Always mark the case of the alternator before disassembly to be assured of correct reassembly.
  • Figure 55-15 Explanation of clock positions. Because the four through bolts are equally spaced, it is possible for an alternator to be installed in one of four different clock positions. The connector position is determined by viewing the alternator from the diode end with the threaded adjusting lug in the up or 12 o 'clock position. Select the 3 o'clock, 6 o'clock, 9 o'clock, or 12 o'clock position to match the unit being replaced.
  • Figure 55-16 Testing an alternator rotor using an ohmmeter.
  • Figure 55-17 If the ohmmeter reads infinity between any two of the three stator windings, the stator is open and, therefore, defective. The ohmmeter should read infinity between any stator lead and the steel laminations. If the reading is less than infinity, the stator is grounded. Stator windings cannot be tested if shorted because the normal resistance is very low.
  • Figure 55-18 Typical diode trio. If one leg of a diode trio is open, the alternator may produce close to normal output, but the charge indicator light on the dash will be on dimly.
  • Figure 55-19 A typical rectifier bridge that contains all six diodes in one replaceable assembly.
  • Figure 55-20 A brush holder assembly with new brushes installed. The holes in the brushes are used to hold the brushes up in the holder when it is installed in the alternator. After the rotor has been installed, the retaining pin is removed which allows the brushes to contact the slip rings of the rotor.
  • ALTERNATOR OVERHAUL 1 Before the alternator is disassembled, it is spin tested and connected to a scope to check for possible defective components.
  • ALTERNATOR OVERHAUL 2 The scope pattern shows that the voltage output is far from being a normal pattern. This pattern indicates serious faults in the rectifier diodes.
  • ALTERNATOR OVERHAUL 3 The first step is to remove the drive pulley. This rebuilder is using an electric impact wrench to accomplish the task.
  • ALTERNATOR OVERHAUL 4 Carefully inspect the drive galley for damage of embedded rubber from the drive belt. The slightest fault can cause a vibration, noise, or possible damage to the alternator.
  • ALTERNATOR OVERHAUL 5 Remove the external fan (if equipped) and then the spacers as shown.
  • ALTERNATOR OVERHAUL 6 Next pop off the plastic cover (shield) covering the stator/rectifier connection.
  • ALTERNATOR OVERHAUL 7 After the cover has been removed, the stator connections to the rectifier can be seen.
  • ALTERNATOR OVERHAUL 8 Using a diagonal cutter, cut the weld to separate the stator from the rectifier.
  • ALTERNATOR OVERHAUL 9 Before separating the halves of the case, this technician uses a punch to mark both halves.
  • ALTERNATOR OVERHAUL 10 After the case has been marked, the through-bolts are removed.
  • ALTERNATOR OVERHAUL 11 The drive-end housing and the stator are being separated from the rear (slip-ring-end) housing.
  • ALTERNATOR OVERHAUL 12 The stator is checked by visual inspection for discoloration or other physical damage, and then checked with an ohmmeter to see if the windings are shorted-to-ground.
  • ALTERNATOR OVERHAUL 13 The front bearing is removed from the drive-end housing using a press.
  • ALTERNATOR OVERHAUL 14 A view of the slip-ring-end (SRE) housing showing the black plastic shield, which helps direct air flow across the rectifier.
  • ALTERNATOR OVERHAUL 15 A punch is used to dislodge the plastic shield retaining clips.
  • ALTERNATOR OVERHAUL 16 After the shield has been removed, the rectifier, regulator, and brush holder assembly can be removed by removing the retaining screws.
  • ALTERNATOR OVERHAUL 17 The hear transfer grease is visible when the rectifier assembly is lifted out of the rear housing.
  • ALTERNATOR OVERHAUL 18 The parts are placed into a tumbler where ceramic stones and a water-based solvent are used to clean the parts.
  • ALTERNATOR OVERHAUL 19 This rebuilder is painting the housing using a high-quality industrial grade spray paint to make the rebuilt alternator look like new.
  • ALTERNATOR OVERHAUL 20 The slip rings on the rotor are being machined on a lathe.
  • ALTERNATOR OVERHAUL 21 The rotor is being tested using an ohmmeter. The specifications for the resistance between the slip rings on the CS-130 are 2.2 to 3.5 ohms.
  • ALTERNATOR OVERHAUL 22 The rotor is also tested between the slip ring and the rotor shaft. This reading should be infinity.
  • ALTERNATOR OVERHAUL 23 A new rectifier. This replacement unit is significantly different than the original but is designed to replace the original unit and meets the original factory specifications.
  • ALTERNATOR OVERHAUL 24 Silicone heat transfer compound is applied to the heat sink of the new rectifier.
  • ALTERNATOR OVERHAUL 25 Replacement brushes and springs are assembled into the brush holder.
  • ALTERNATOR OVERHAUL 26 The brushes are pushed into the brush holder and retained by a straight wire, which extends through the rear housing of the alternator. This wire is then pulled out when the unit is assembled.
  • ALTERNATOR OVERHAUL 27 Here is what the CS alternator looks like after installing the new brush holder assembly, rectifier bridge, and voltage regulator.
  • ALTERNATOR OVERHAUL 28 The junction between the rectifier bridge and the voltage regulator is soldered.
  • ALTERNATOR OVERHAUL 29 The plastic deflector shield is snapped back into location using a blunt chisel and a hammer. This shield directs the airflow from the fan over the rectifier bridge and voltage regulator.
  • ALTERNATOR OVERHAUL 30 Before the stator windings can be soldered to the rectifier bridge, the varnish insulation is removed from the ends of the leads.
  • ALTERNATOR OVERHAUL 31 After the stator has been inserted into the rear housing the stator leads are soldered to the copper lugs of the rectifier bridge.
  • ALTERNATOR OVERHAUL 32 New bearings are installed. A spacer is placed between the bearing and the slip rings to help prevent the possibility that the bearing could move on the shaft and short against the slip ring.
  • ALTERNATOR OVERHAUL 33 The slip-ring-end (SRE) housing is aligned with the marks made during disassembly and is pressed into the drive-end (DE) housing.
  • ALTERNATOR OVERHAUL 34 The retaining bolts, which are threaded into the drive-end housing from the back of the alternator are installed.
  • ALTERNATOR OVERHAUL 35 The external fan and drive pulley are installed and the retaining nut is tightened on the rotor shaft.
  • ALTERNATOR OVERHAUL 36 The scope pattern shows that the diodes and stator are functioning correctly and voltage check indicates that the voltage regulator is also functioning correctly.

Transcript

  • 1. CHARGING SYSTEM DIAGNOSIS AND SERVICE 55
  • 2. Objectives
    • The student should be able to:
      • Prepare for ASE Electrical/Electronic Systems (A6) certification test content area “D” (Charging System Diagnosis and Repair).
      • Describe how to perform a charging voltage test.
      • Discuss how to perform an AC ripple voltage test.
      • Explain how to perform an alternator output test.
  • 3. Objectives
    • The student should be able to:
      • Explain how to disassemble an alternator and test its component parts.
      • Discuss how to check the wiring from the alternator to the battery.
      • Describe how to test the operation of a computer-controlled charging system.
  • 4. CHARGING SYSTEM TESTING AND SERVICE
  • 5. Charging System Testing and Service
    • Battery State of Charge
      • Battery must be at least 75% charged before testing.
      • Weak or defective battery causes inaccurate test results.
  • 6. Charging System Testing and Service
    • Charging Voltage Test
      • Easiest way to check charging system voltage at battery.
      • Use a digital multimeter.
  • 7. Charging System Testing and Service
    • Charging Voltage Test
      • STEP 1: Select DC volts.
      • STEP 2: Connect red meter lead to positive (+) terminal, black meter lead to negative (–).
  • 8. Charging System Testing and Service
    • Charging Voltage Test
      • STEP 3: Start engine and increase engine speed to about 2000 RPM (fast idle).
      • STEP 4: Record charging voltage: specifications 13.5 to 15 V.
  • 9. Charging System Testing and Service
    • Charging Voltage Test
      • If voltage too high, check that alternator properly grounded.
      • If voltage lower than specifications: fault with wiring or alternator.
  • 10. Charging System Testing and Service
    • Charging Voltage Test
      • If wiring and connections okay, additional testing required.
      • Replacement of alternator and/or battery often required if charging voltage not within factory specifications.
  • 11. Figure 55-1 The digital multimeter should be set to read DC volts, with the red lead connected to the positive (+) battery terminal and the black meter lead connected to the negative (-) battery terminal.
  • 12. Charging System Testing and Service
    • Scan Testing the Charging Circuit
      • Computer-controlled charging system can be diagnosed using scan tool.
      • Can also monitor output voltage to check system operating correctly.
    ?
  • 13. Figure 55-2 A scan tool can be used to diagnose charging system problems.
  • 14. DRIVE BELT INSPECTION AND ADJUSTMENT
  • 15. Drive Belt Inspection and Adjustment
    • Belt Visual Inspection
      • Regularly inspect belts and replace as needed.
      • Replace serpentine belt with more than 3 cracks in any one rib in a 3-in. span.
  • 16. Figure 55-4 This accessory drive belt is worn and requires replacement. Newer belts are made from ethylene propylene diene monomer (EPDM). This rubber does not crack like older belts and may not show wear even though the ribs do wear and can cause slippage.
  • 17. Drive Belt Inspection and Adjustment
    • Belt Tension Measurement
      • Install belt, operate engine with all accessories on at least 5 minutes.
      • Adjust tension of belt to factory specifications.
  • 18. Drive Belt Inspection and Adjustment
    • Belt Tension Measurement
      • Ways manufacturers specify belt tension within factory specifications.
        • Belt tension gauge
        • Marks on tensioner
  • 19. Drive Belt Inspection and Adjustment
    • Belt Tension Measurement
      • Ways manufacturers specify belt tension within factory specifications.
        • Torque wrench reading
        • Deflection
  • 20. Figure 55-5 Check service information for the exact marks where the tensioner should be located for proper belt tension.
  • 21. Chart 55-1 Typical belt tension for various widths of belts. Tension is the force needed to depress the belt as displayed on a belt tension gauge.
  • 22. AC RIPPLE VOLTAGE CHECK
  • 23. AC Ripple Voltage Check
    • Principles
      • Good alternator produces very little AC voltage or current output.
      • Diodes rectify or convert most AC voltage into DC voltage.
  • 24. AC Ripple Voltage Check
    • Principles
      • Excessive AC voltage (AC ripple) undesirable.
      • Indicates fault with rectifier diodes or stator windings.
  • 25. AC Ripple Voltage Check
    • Testing AC Ripple Voltage
      • STEP 1: Set digital meter to read AC volts.
      • STEP 2: Start engine and operate at 2000 RPM (fast idle).
  • 26. AC Ripple Voltage Check
    • Testing AC Ripple Voltage
      • STEP 3: Connect voltmeter leads to positive and negative battery terminals.
      • STEP 4: Turn on headlights to provide electrical load on alternator.
  • 27. AC Ripple Voltage Check
    • Testing AC Ripple Voltage
      • Voltmeter reads less than 400 mV (0.4 volt) AC: diodes good.
      • Reading over 500 mV (0.5 volt) AC: diodes defective.
  • 28. Figure 55-7 Testing AC ripple at the output terminal of the alternator is more accurate than testing at the battery due to the resistance of the wiring between the alternator and the battery. The reading shown on the meter, set to AC volts, is only 78 mV (0.078 V), far below what the reading would be if a diode were defective.
  • 29. TESTING AC RIPPLE CURRENT
  • 30. Testing AC Ripple Current
    • Testing AC Ripple Current
      • Mini clamp-on meter that measures AC amperes can check alternator.
      • Alternator should produce less than 10% of rated amperage output in AC ripple.
  • 31. Testing AC Ripple Current
    • Test Procedure
      • STEP 1: Start engine, turn on lights to create electrical load.
      • STEP 2: Place clamp of mini-meter around either all positive (+) or all negative (–) battery cables.
  • 32. Testing AC Ripple Current
    • Test Procedure
      • STEP 3: Switch meter to read AC amperes; record reading.
      • STEP 4: Reading of greater than 10 amperes AC indicates defective alternator diodes.
  • 33. Figure 55-9 A mini clamp-on meter can be used to measure alternator output as shown here (105.2 Amp). Then the meter can be used to check AC current ripple by selecting AC Amps on the rotary dial. AC ripple current should be less than 10% of the DC current output.
  • 34. CHARGING SYSTEM VOLTAGE DROP TESTING
  • 35. Charging System Voltage Drop Testing
    • Alternator Wiring
      • Must be good electrical connections between battery positive terminal and alternator output terminal.
      • Alternator must also be properly grounded to engine block.
  • 36. Charging System Voltage Drop Testing
    • Voltage Drop Test Procedure
      • STEP 1: Start engine and operate at 2000 RPM (fast idle).
      • STEP 2: Turn on headlights to create electrical load.
  • 37. Charging System Voltage Drop Testing
    • Voltage Drop Test Procedure
      • STEP 3: Set voltmeter to read DC volts.
      • STEP 4: Connect positive test lead to output terminal of alternator.
  • 38. Charging System Voltage Drop Testing
    • Voltage Drop Test Procedure
      • STEP 5: Attach negative test lead to positive post of battery.
        • Reading less than 0.4 volt (400 mV): all wiring and connections satisfactory.
  • 39. Charging System Voltage Drop Testing
    • Voltage Drop Test Procedure
      • STEP 5: Attach negative test lead to positive post of battery.
        • Reading higher than 0.4 volt: excessive resistance (voltage drop) between alternator and battery.
        • Reading battery voltage: open circuit between battery and alternator.
  • 40. Figure 55-10 Voltmeter hookup to test the voltage drop of the charging circuit.
  • 41. ALTERNATOR OUTPUT TEST
  • 42. Alternator Output Test
    • Preliminary Checks
      • Test measures current (amperes) of alternator.
      • Charging circuit may produce correct voltage, but not adequate amperage.
  • 43. Alternator Output Test
    • Preliminary Checks
      • First check condition of alternator drive belt.
      • Replace or tighten belt if needed.
  • 44. Alternator Output Test
    • Carbon Pile Test Procedure
      • Used to load test battery and/or alternator.
        • STEP 1: Connect starting and charging test leads according to instructions.
  • 45. Alternator Output Test
    • Carbon Pile Test Procedure
      • Used to load test battery and/or alternator.
        • STEP 2: Turn off all electrical accessories.
        • STEP 3: Start engine and operate at 2000 RPM (fast idle).
  • 46. Alternator Output Test
    • Carbon Pile Test Procedure
      • Used to load test battery and/or alternator
        • STEP 4: Turn load increase control slowly to obtain highest reading on ammeter.
        • STEP 5: Do not allow voltage to drop below 12.6 volts.
  • 47. Alternator Output Test
    • Carbon Pile Test Procedure
      • Used to load test battery and/or alternator
        • STEP 6: Add 5 to 7 amperes (current used by ignition).
        • STEP 7: Compare output reading to factory specifications.
  • 48. Figure 55-11 A typical tester used to test batteries as well as the cranking and charging system. Always follow the operating instructions.
  • 49. MINIMUM REQUIRED ALTERNATOR OUTPUT
  • 50. Minimum Required Alternator Output
    • Purpose
      • Charging systems must be able to supply electrical demands electrical system.
      • Otherwise, battery will be drained.
  • 51. Minimum Required Alternator Output
    • Purpose
      • To determine minimum load requirements, connect inductive ammeter probe around either battery cable or alternator output cable.
  • 52. Figure 55-12 The best place to install a charging system tester amp probe is around the alternator output terminal wire, as shown.
  • 53. Minimum Required Alternator Output
    • Procedure
      • Start engine and operate to about 2000 RPM (fast idle).
      • Turn heat selector to air conditioning.
      • Turn blower motor to high speed.
  • 54. Minimum Required Alternator Output
    • Procedure
      • Turn headlights on bright.
      • Turn on rear defogger.
      • Turn on windshield wipers.
  • 55. Minimum Required Alternator Output
    • Procedure
      • Turn on other accessories used continuously.
      • Observe ammeter: current indicated is load alternator is able to exceed to keep battery fully charged.
  • 56. Minimum Required Alternator Output
    • Test Results
      • Minimum acceptable alternator output 5 amperes greater than accessory load.
      • Negative (discharge) reading: alternator can 't supply current needed.
  • 57. ALTERNATOR REMOVAL
  • 58. Alternator Removal
    • STEP 1: With test light or voltmeter, check for battery voltage at output terminal of alternator.
    • STEP 2: If no voltage, check for blown fusible link or other electrical circuit fault.
  • 59. Alternator Removal
    • STEP 3: Disconnect negative (–) terminal from battery.
    • STEP 4: Remove alternator drive belt.
    • STEP 5: Remove electrical wiring, fasteners, spacers, and brackets as necessary.
    • STEP 6: Remove alternator.
  • 60. Figure 55-13 Replacing an alternator is not always as easy as it is from a Buick with a 3800 V-6, where the alternator is easy to access. Many alternators are difficult to access, and require the removal of other components.
  • 61. ALTERNATOR DISASSEMBLY
  • 62. Alternator Disassembly
    • Disassembly Procedure
      • STEP 1: Mark case with scratch or chalk to ensure proper reassembly.
      • STEP 2: Remove through bolts.
  • 63. Alternator Disassembly
    • Disassembly Procedure
      • STEP 3: Carefully separate two halves; stator windings must stay with rear case.
      • STEP 4: Remove rectifier assembly and voltage regulator.
    ?
  • 64. Figure 55-14 Always mark the case of the alternator before disassembly to be assured of correct reassembly.
  • 65. Figure 55-15 Explanation of clock positions. Because the four through bolts are equally spaced, it is possible for an alternator to be installed in one of four different clock positions. The connector position is determined by viewing the alternator from the diode end with the threaded adjusting lug in the up or 12 o 'clock position. Select the 3 o'clock, 6 o'clock, 9 o'clock, or 12 o'clock position to match the unit being replaced.
  • 66. Alternator Disassembly
    • Rotor Testing
      • Slip rings on rotor should be smooth and round.
      • If grooved, can be machined to provide suitable surface for brushes.
  • 67. Alternator Disassembly
    • Rotor Testing
      • If dirty, can be cleaned with 400-grit or fine emery (polishing) cloth.
      • Measure resistance between slip rings using ohmmeter.
        • Resistance between either slip ring and steel rotor shaft should be infinity (OL); if continuity, rotor shorted to ground.
  • 68. Alternator Disassembly
    • Rotor Testing
      • If dirty, can be cleaned with 400-grit or fine emery (polishing) cloth.
      • Measure resistance between slip rings using ohmmeter.
        • Rotor resistance range normally between 2.4 and 6 ohms.
        • If resistance below specification, rotor is shorted.
  • 69. Alternator Disassembly
    • Rotor Testing
      • Measure resistance between slip rings using ohmmeter.
        • If resistance above specification, rotor connections corroded or open.
      • If rotor bad, must be replaced or repaired.
  • 70. Figure 55-16 Testing an alternator rotor using an ohmmeter.
  • 71. Alternator Disassembly
    • Stator Testing
      • Disconnect from diodes (rectifiers) before testing.
      • Ohmmeter can be used to check stator.
  • 72. Alternator Disassembly
    • Stator Testing
      • Should be low resistance at all three stator leads (continuity).
      • Should not be continuity between any stator lead and metal stator core.
      • If continuity, stator is shorted-to-ground and must be repaired or replaced.
  • 73. Figure 55-17 If the ohmmeter reads infinity between any two of the three stator windings, the stator is open and, therefore, defective. The ohmmeter should read infinity between any stator lead and the steel laminations. If the reading is less than infinity, the stator is grounded. Stator windings cannot be tested if shorted because the normal resistance is very low.
  • 74. Alternator Disassembly
    • Testing the Diode Trio
      • If one of three diodes defective (usually open), alternator may produce close-to-normal output.
      • However, charge indicator light will be on dimly.
  • 75. Alternator Disassembly
    • Testing the Diode Trio
      • Test with digital multimeter set to diode-check position.
      • Multimeter should indicate 0.5 to 0.7 V (500 to 700 mV) one way.
  • 76. Alternator Disassembly
    • Testing the Diode Trio
      • Should read OL (overlimit) after reversing test leads and touching all three connectors.
  • 77. Figure 55-18 Typical diode trio. If one leg of a diode trio is open, the alternator may produce close to normal output, but the charge indicator light on the dash will be on dimly.
  • 78. TESTING THE RECTIFIER
  • 79. Testing the Rectifier
    • Terminology
      • Rectifier usually has six diodes (three positive, three negative).
  • 80. Testing the Rectifier
    • Meter Setup
      • Test using multimeter that is set to “diode check” position.
      • For each diode, test whether allows current to flow in only one direction.
  • 81. Testing the Rectifier
    • Meter Setup
      • For accurate testing, separate diodes electrically from other alternator components.
  • 82. Figure 55-19 A typical rectifier bridge that contains all six diodes in one replaceable assembly.
  • 83. Testing the Rectifier
    • Testing Procedure
      • Connect leads of meter to leads of diode; read meter.
      • Reverse test leads.
  • 84. Testing the Rectifier
    • Testing Procedure
      • Good diode.
        • High resistance (OL) one way (reverse bias).
        • Low voltage drop of 0.5 to 0.7 V (500 to 700 mV) other way (forward bias).
  • 85. Testing the Rectifier
    • Results
      • Open or shorted diodes must be replaced.
  • 86. REASSEMBLING THE ALTERNATOR
  • 87. Reassembling the Alternator
    • Brush Holder Replacement
      • Alternator carbon brushes often last for many years.
      • Alternator brushes should be inspected when alternator disassembled.
      • Replace when worn to less than 1/2 in. long.
  • 88. Figure 55-20 A brush holder assembly with new brushes installed. The holes in the brushes are used to hold the brushes up in the holder when it is installed in the alternator. After the rotor has been installed, the retaining pin is removed which allows the brushes to contact the slip rings of the rotor.
  • 89. Reassembling the Alternator
    • Bearing Service and Replacement
      • Bearings must support rotor and reduce friction.
      • Old or defective bearing can sometimes be pushed out of front housing.
  • 90. Reassembling the Alternator
    • Bearing Service and Replacement
      • Replacement pushed in.
      • Replacement bearings usually prelubricated and seated.
  • 91. Reassembling the Alternator
    • Alternator Assembly
      • STEP 1: Internally mounted brushes: insert wire through holes in brush holder to hold brushes against springs.
      • STEP 2: Install rotor, front-end frame in proper alignment with mark made on outside of alternator housing.
  • 92. Reassembling the Alternator
    • Alternator Assembly
      • STEP 3: Install through bolts.
      • STEP 4: Spin alternator pulley to check for free rotation.
  • 93. Reassembling the Alternator
    • Alternator Assembly
      • STEP 5: Remove brush holder pin and spin again.
      • STEP 6: Test alternator on bench tester before reinstalling in vehicle.
  • 94. ALTERNATOR INSTALLATION
  • 95. Alternator Installation
    • STEP 1: Verify replacement alternator is correct unit for vehicle.
    • STEP 2: Install alternator wiring on alternator and install alternator.
    • STEP 3: Check condition of drive belt and replace, if necessary.
  • 96. Alternator Installation
    • STEP 4: Install drive belt over drive pulley.
    • STEP 5: Properly tension drive belt.
    • STEP 6: Tighten all fasteners to factory specifications.
  • 97. Alternator Installation
    • STEP 7: Double-check that all fasteners are correctly tightened.
    • STEP 8: Remove all tools from engine compartment area.
    • STEP 9: Reconnect negative battery cable.
    • STEP 10: Start engine and verify proper charging circuit operation.
  • 98. ALTERNATOR OVERHAUL 1 Before the alternator is disassembled, it is spin tested and connected to a scope to check for possible defective components.
  • 99. ALTERNATOR OVERHAUL 2 The scope pattern shows that the voltage output is far from being a normal pattern. This pattern indicates serious faults in the rectifier diodes.
  • 100. ALTERNATOR OVERHAUL 3 The first step is to remove the drive pulley. This rebuilder is using an electric impact wrench to accomplish the task.
  • 101. ALTERNATOR OVERHAUL 4 Carefully inspect the drive galley for damage of embedded rubber from the drive belt. The slightest fault can cause a vibration, noise, or possible damage to the alternator.
  • 102. ALTERNATOR OVERHAUL 5 Remove the external fan (if equipped) and then the spacers as shown.
  • 103. ALTERNATOR OVERHAUL 6 Next pop off the plastic cover (shield) covering the stator/rectifier connection.
  • 104. ALTERNATOR OVERHAUL 7 After the cover has been removed, the stator connections to the rectifier can be seen.
  • 105. ALTERNATOR OVERHAUL 8 Using a diagonal cutter, cut the weld to separate the stator from the rectifier.
  • 106. ALTERNATOR OVERHAUL 9 Before separating the halves of the case, this technician uses a punch to mark both halves.
  • 107. ALTERNATOR OVERHAUL 10 After the case has been marked, the through-bolts are removed.
  • 108. ALTERNATOR OVERHAUL 11 The drive-end housing and the stator are being separated from the rear (slip-ring-end) housing.
  • 109. ALTERNATOR OVERHAUL 12 The stator is checked by visual inspection for discoloration or other physical damage, and then checked with an ohmmeter to see if the windings are shorted-to-ground.
  • 110. ALTERNATOR OVERHAUL 13 The front bearing is removed from the drive-end housing using a press.
  • 111. ALTERNATOR OVERHAUL 14 A view of the slip-ring-end (SRE) housing showing the black plastic shield, which helps direct air flow across the rectifier.
  • 112. ALTERNATOR OVERHAUL 15 A punch is used to dislodge the plastic shield retaining clips.
  • 113. ALTERNATOR OVERHAUL 16 After the shield has been removed, the rectifier, regulator, and brush holder assembly can be removed by removing the retaining screws.
  • 114. ALTERNATOR OVERHAUL 17 The hear transfer grease is visible when the rectifier assembly is lifted out of the rear housing.
  • 115. ALTERNATOR OVERHAUL 18 The parts are placed into a tumbler where ceramic stones and a water-based solvent are used to clean the parts.
  • 116. ALTERNATOR OVERHAUL 19 This rebuilder is painting the housing using a high-quality industrial grade spray paint to make the rebuilt alternator look like new.
  • 117. ALTERNATOR OVERHAUL 20 The slip rings on the rotor are being machined on a lathe.
  • 118. ALTERNATOR OVERHAUL 21 The rotor is being tested using an ohmmeter. The specifications for the resistance between the slip rings on the CS-130 are 2.2 to 3.5 ohms.
  • 119. ALTERNATOR OVERHAUL 22 The rotor is also tested between the slip ring and the rotor shaft. This reading should be infinity.
  • 120. ALTERNATOR OVERHAUL 23 A new rectifier. This replacement unit is significantly different than the original but is designed to replace the original unit and meets the original factory specifications.
  • 121. ALTERNATOR OVERHAUL 24 Silicone heat transfer compound is applied to the heat sink of the new rectifier.
  • 122. ALTERNATOR OVERHAUL 25 Replacement brushes and springs are assembled into the brush holder.
  • 123. ALTERNATOR OVERHAUL 26 The brushes are pushed into the brush holder and retained by a straight wire, which extends through the rear housing of the alternator. This wire is then pulled out when the unit is assembled.
  • 124. ALTERNATOR OVERHAUL 27 Here is what the CS alternator looks like after installing the new brush holder assembly, rectifier bridge, and voltage regulator.
  • 125. ALTERNATOR OVERHAUL 28 The junction between the rectifier bridge and the voltage regulator is soldered.
  • 126. ALTERNATOR OVERHAUL 29 The plastic deflector shield is snapped back into location using a blunt chisel and a hammer. This shield directs the airflow from the fan over the rectifier bridge and voltage regulator.
  • 127. ALTERNATOR OVERHAUL 30 Before the stator windings can be soldered to the rectifier bridge, the varnish insulation is removed from the ends of the leads.
  • 128. ALTERNATOR OVERHAUL 31 After the stator has been inserted into the rear housing the stator leads are soldered to the copper lugs of the rectifier bridge.
  • 129. ALTERNATOR OVERHAUL 32 New bearings are installed. A spacer is placed between the bearing and the slip rings to help prevent the possibility that the bearing could move on the shaft and short against the slip ring.
  • 130. ALTERNATOR OVERHAUL 33 The slip-ring-end (SRE) housing is aligned with the marks made during disassembly and is pressed into the drive-end (DE) housing.
  • 131. ALTERNATOR OVERHAUL 34 The retaining bolts, which are threaded into the drive-end housing from the back of the alternator are installed.
  • 132. ALTERNATOR OVERHAUL 35 The external fan and drive pulley are installed and the retaining nut is tightened on the rotor shaft.
  • 133. ALTERNATOR OVERHAUL 36 The scope pattern shows that the diodes and stator are functioning correctly and voltage check indicates that the voltage regulator is also functioning correctly.
  • 134. FREQUENTLY ASKED QUESTION
    • What Is a Full-Fielding Test?
      • Full fielding is a procedure used on older noncomputerized vehicles for bypassing the voltage regulator that could be used to determine if the alternator is capable of producing its designed output. This test is no longer performed for the following reasons.
    ? BACK TO PRESENTATION
    • The voltage regulator is built into the alternator, therefore requiring that the entire assembly be replaced even if just the regulator is defective.
    • When the regulator is bypassed, the alternator can produce a high voltage (over 100 volts in some cases) which could damage all of the electronic circuits in the vehicle.
    • Always follow the vehicle manufacturer 's recommended testing procedures.
  • 135. TECH TIP
    • Use a Test Light to Check for a Defective Fusible Link
      • Most alternators use a fusible link or mega fuse between the output terminal and the positive (+) terminal of the battery. If this fusible link or fuse is defective (blown), then the charging system will not operate at all.
    • Many alternators have been replaced repeatedly because of a blown fusible link that was not discovered until later. A quick and easy test to check if the fusible link is okay is to touch a test light to the output terminal. With the other end of the test light attached to a good ground, the fusible link or mega fuse is okay if the light lights. This test confirms that the circuit between the alternator and the battery has continuity.
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      • Figure 55-3 Before replacing an alternator, the wise technician checks that battery voltage is present at the output and battery voltage sense terminals. If not, then there is a fault in the wiring.
  • 136. TECH TIP
    • The Hand Cleaner Trick
      • Lower-than-normal alternator output could be the result of a loose or slipping drive belt. All belts (V and serpentine multigroove) use an interference angle between the angle of the Vs of the belt and the angle of the Vs on the pulley. As the belt wears, the interference angles are worn off of both edges of the belt.
    BACK TO PRESENTATION
    • As a result, the belt may start to slip and make a squealing sound even if tensioned properly.
    • A common trick used to determine if the noise is belt related is to use grit-type hand cleaner or scouring powder. With the engine off, sprinkle some powder onto the pulley side of the belt. Start the engine. The excess powder will fly into the air, so get away from under the hood when the engine starts. If the belts are now quieter, you know that it was the glazed belt that made the noise.
    • The noise can sound exactly like a noisy bearing. Therefore, before you start removing and replacing parts, try the hand cleaner trick.
    • Often, the grit from the hand cleaner will remove the glaze from the belt and the noise will not return. However, if the belt is worn or loose, the noise will return and the belt should be replaced. A fast, alternative method to see if the noise is from the belt is to spray water from a squirt bottle at the belt with the engine running.
    • If the noise stops, the belt is the cause of the noise. The water quickly evaporates and, therefore, unlike the gritty hand cleaner, water simply finds the problem—it does not provide a short-term fix.
  • 137. TECH TIP
    • Check the Overrunning Clutch
      • If low or no alternator output is found, remove the alternator drive belt and check the overrunning alternator pulley (OAP) or overrunning alternator dampener (OAD) for proper operation. Both types of overrunning clutches use a one-way clutch.
    BACK TO PRESENTATION
    • Therefore, the pulley should freewheel in one direction and rotate the alternator rotor when rotated in the opposite direction.
      • Figure 55-6 This overrunning alternator dampener (OAD) is longer than an overrunning alternator pulley (OAP) because it contains a dampener spring as well as a one way clutch. Be sure to check that it locks in one direction.
  • 138. TECH TIP
    • The Lighter Plug Trick
      • Battery voltage measurements can be read through the lighter socket. Simply construct a test tool using a lighter plug at one end of a length of two-conductor wire and the other end connected to a double banana plug.
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    • The double banana plug will fit most meters in the common (COM) terminal and the volt terminal of the meter. This is handy to use while road testing the vehicle under real-life conditions. Both DC voltage and AC ripple voltage can be measured.
      • Figure 55-8 Charging system voltage can be easily checked at the lighter plug by connecting a lighter plug to the voltmeter through a double banana plug.
  • 139. TECH TIP
    • Use a Fused Jumper Wire as a Diagnostic Tool
      • When diagnosing an alternator charging problem, try using a fused jumper wire to connect the positive and negative terminals of the alternator directly to the positive and negative terminals of the battery.
    BACK TO PRESENTATION
    • If a definite improvement is noticed, the problem is in the wiring of the vehicle. High resistance, due to corroded connections or loose grounds, can cause low alternator output, repeated regulator failures, slow cranking, and discharged batteries. A voltage drop test of the charging system can also be used to locate excessive resistance (high voltage drop) in the charging circuit, but using a fused jumper wire is often faster and easier.
  • 140. TECH TIP
    • Bigger Is Not Always Better
      • Many technicians are asked to install a higher output alternator to allow the use of emergency equipment or other high-amperage equipment such as a high-wattage sound system.
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    • Although many higher output units can be physically installed, it is important not to forget to upgrade the wiring and the fusible link(s) in the alternator circuit. Failure to upgrade the wiring could lead to overheating. The usual failure locations are at junctions or electrical connectors.
  • 141. TECH TIP
    • The Sniff Test
      • When checking for the root cause of an alternator failure, one test that a technician could do is to sniff (smell) the alternator. If the alternator smells like a dead rat (rancid smell), the stator windings have been overheated by trying to charge a discharged or defective battery.
    BACK TO PRESENTATION
    • If the battery voltage is continuously low, the voltage regulator will continue supplying full-field current to the alternator. The voltage regulator is designed to cycle on and off to maintain a narrow charging system voltage range.
    • If the battery voltage is continually below the cutoff point of the voltage regulator, the alternator is continually producing current in the stator windings. This constant charging can often overheat the stator and burn the insulating varnish covering the stator windings. If the alternator fails the sniff test, the technician should replace the stator and other alternator components that are found to be defective and replace or recharge and test the battery.
  • 142. FREQUENTLY ASKED QUESTION
    • What Is a “Clock Position”?
      • Most alternators of a particular manufacturer can be used on a variety of vehicles, which may require wiring connections placed in various locations. For example, a Chevrolet and a Buick alternator may be identical except for the position of the rear section containing the electrical connections.
    ?
    • The four through bolts that hold the two halves together are equally spaced; therefore, the rear alternator housing can be installed in any one of four positions to match the wiring needs of various models. Always check the clock position of the original and be sure that it matches the replacement unit.
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      • Figure 55-15 Explanation of clock positions. Because the four through bolts are equally spaced, it is possible for an alternator to be installed in one of four different clock positions. The connector position is determined by viewing the alternator from the diode end with the threaded adjusting lug in the up or 12 o 'clock position. Select the 3 o'clock, 6 o'clock, 9 o'clock, or 12 o'clock position to match the unit being replaced.
  • 143. REAL WORLD FIX
    • The Two-Minute Alternator Repair
      • A Chevrolet pickup truck was brought to a shop for routine service. The customer stated that the battery required a jump start after a weekend of sitting. The technician tested the battery and charging system voltage using a small handheld digital multimeter.
    BACK TO PRESENTATION
    • The battery voltage was 12.4 volts (about 75% charged), but the charging voltage was also 12.4 volts at 2000 RPM. Because normal charging voltage should be 13.5 to 15 volts, it was obvious that the charging system was not operating correctly.
    • The technician checked the dash and found that the "charge" light was not on. Before removing the alternator for service, the technician checked the wiring connection on the alternator. When the connector was removed, it was discovered to be rusty. After the contacts were cleaned, the charging system was restored to normal operation. The technician had learned that the simple things should always be checked first before tearing into a big (or expensive) repair.